Source: ECO 201, University of Florida
Tags: fiscal policy, monetary policy, automatic stabilizers, labour income tax, capital income tax, government spending multiplier, tax multiplier, aggregate demand, aggregate supply, AD-AS model, expansionary policy, contractionary policy, crowding out, budget deficit
Difficulty: Intermediate Prerequisites: Basic understanding of GDP components (C + I + G + NX), supply and demand, and the circular flow model. If those feel unfamiliar, review your introductory macro notes on national income accounting first.
Fiscal policy is one of the two main levers governments use to influence macroeconomic outcomes, the other being monetary policy. This section covers how changes in government spending and taxation ripple through the economy, why some fiscal responses happen automatically, and how to model those effects using the AD-AS framework. If you have been away from the course for a few weeks, know that everything here builds on the GDP expenditure identity and the basic notion that one person's spending is another person's income.
Fiscal policy works through government spending and taxation. Spending increases or tax cuts boost aggregate demand (expansionary), while spending cuts or tax increases reduce it (contractionary). Multiplier effects amplify these changes, but the spending multiplier is larger than the tax multiplier for a given dollar amount. Automatic stabilisers smooth the cycle without anyone passing new legislation.
Fiscal policy
The use of government spending and taxation to influence macroeconomic conditions such as output, employment, and the price level. Think of it as the government adjusting its own budget to steer the economy.
Monetary policy
The use of central bank tools (interest rates, money supply) to influence macroeconomic conditions. In simple terms, fiscal policy is about the government's wallet; monetary policy is about the central bank's control of money and credit.
Automatic stabilisers (automatic fiscal policies)
Government revenue and spending mechanisms that adjust automatically with economic conditions, without new legislation. Think of them as shock absorbers built into the tax and benefits system.
Discretionary fiscal policy
Deliberate changes in government spending or taxation enacted by legislation. In simple terms, this is when Parliament or Congress actively decides to change the budget.
Government spending multiplier
The ratio of the change in GDP to the initial change in government spending. It tells you how much total output changes for each pound or dollar the government spends.
Tax multiplier
The ratio of the change in GDP to an initial change in taxes. It is smaller (in absolute value) than the spending multiplier because some of the tax cut is saved rather than spent.
Marginal propensity to consume (MPC)
The fraction of each additional pound or dollar of income that households spend rather than save. If the MPC is 0.8, people spend 80p of every extra £1.
Marginal propensity to save (MPS)
The fraction of each additional pound or dollar of income that households save. MPS = 1 − MPC.
Crowding out
The reduction in private investment that occurs when increased government borrowing pushes up interest rates. In simple terms, the government competes with businesses for loanable funds, and businesses lose some of that competition.
Expansionary fiscal policy
Policy that increases aggregate demand, typically through higher government spending or lower taxes. Used during recessions to boost output and employment.
Contractionary fiscal policy
Policy that decreases aggregate demand, typically through lower government spending or higher taxes. Used during inflationary periods to cool the economy.
Fiscal policy is conducted by the government (executive and legislative branches). Monetary policy is conducted by the central bank (e.g. the Federal Reserve).
Fiscal policy operates through the government budget: spending (G) and taxes (T). Monetary policy operates through the money supply and interest rates.
Both aim to stabilise the economy, but they work through different channels and have different time lags.
Fiscal policy has a longer implementation lag (legislation takes time) but can target specific sectors.
Monetary policy can be adjusted more quickly but affects the economy more broadly.
These are features of the tax and transfer system that expand fiscal policy during downturns and contract it during booms, with no new legislation required.
Key mechanisms:
Progressive income taxes: As incomes fall in a recession, people move into lower tax brackets, so tax revenue drops automatically. This leaves more disposable income in people's hands, partially cushioning the downturn.
Unemployment insurance: When unemployment rises, more people claim benefits. Government spending on transfers rises automatically, supporting consumption.
Welfare and means-tested transfers: Similar to unemployment insurance, these payments increase when more people qualify during downturns.
During a boom, the reverse happens: rising incomes push people into higher brackets, and fewer people claim benefits, automatically slowing spending growth.
Automatic stabilisers reduce the amplitude of business cycles but cannot eliminate them entirely.
A labour income tax is levied on wages and salaries.
Tax increase on labour income:
Reduces the after-tax wage, making work less attractive at the margin.
Labour supply decreases (or grows more slowly), leading to lower employment and lower output.
The pre-tax wage may rise slightly as labour becomes scarcer, but the after-tax wage still falls.
Overall effect: lower employment, lower output, ambiguous effect on the pre-tax wage (depends on elasticities).
Tax cut on labour income:
Raises the after-tax wage, encouraging more labour supply.
Employment and output tend to increase.
The size of these effects depends on the elasticity of labour supply. If workers are relatively unresponsive to wage changes (inelastic supply), the employment effects are smaller.
A capital income tax is levied on returns to capital: interest, dividends, capital gains.
Tax increase on capital income:
Reduces the after-tax return on investment, discouraging saving and investment.
Investment falls, reducing the capital stock over time and lowering potential output.
The real interest rate adjusts: the pre-tax return must rise to compensate investors, pushing up borrowing costs.
Tax cut on capital income:
Raises the after-tax return, encouraging more investment.
Over time, a larger capital stock raises output and productivity.
Key distinction: labour income taxes primarily affect the supply side through employment; capital income taxes primarily affect the supply side through investment and capital accumulation.
The spending multiplier tells you the total change in GDP from a £1 change in government spending.
Formula: Spending multiplier = 1 / (1 − MPC)
Example: If MPC = 0.8, the spending multiplier is 1 / (1 − 0.8) = 1 / 0.2 = 5. A £100m increase in G raises GDP by £500m.
Intuition: the government spends £100m, which becomes income for someone. That person spends 80% (£80m), which becomes income for someone else, who spends 80% of that (£64m), and so on. The chain of spending adds up to a multiple of the original injection.
The tax multiplier tells you the total change in GDP from a £1 change in taxes.
Formula: Tax multiplier = −MPC / (1 − MPC)
Example: If MPC = 0.8, the tax multiplier is −0.8 / 0.2 = −4. A £100m tax cut raises GDP by £400m.
The tax multiplier is smaller in absolute value than the spending multiplier. Why? Because a tax cut first becomes extra disposable income, and households save a fraction of it (MPS). Only the spent portion enters the multiplier chain. A spending increase, by contrast, enters the economy at full value on the first round.
Balanced-budget multiplier: If the government increases spending by £100m and raises taxes by £100m simultaneously, GDP still rises by £100m. The balanced-budget multiplier equals 1.
Aggregate Demand (AD): The total quantity of goods and services demanded at each price level. AD slopes downward.
Short-Run Aggregate Supply (SRAS): The total quantity of goods and services firms supply at each price level in the short run. SRAS slopes upward.
Long-Run Aggregate Supply (LRAS): Vertical at the natural (potential) level of output. In the long run, output is determined by resources and technology, not the price level.
Expansionary fiscal policy (spending increase or tax cut):
Shifts AD to the right.
In the short run: output rises, employment rises, the price level rises.
In the long run: wages and input costs adjust upward, SRAS shifts left, output returns toward potential, and the price level is permanently higher.
Contractionary fiscal policy (spending cut or tax increase):
Shifts AD to the left.
In the short run: output falls, employment falls, the price level falls (or rises more slowly).
In the long run: wages adjust downward, SRAS shifts right, output returns toward potential, and the price level is permanently lower.
Be prepared to draw and label these shifts. Exam questions frequently ask you to show the short-run and long-run equilibrium on the same diagram.
Formula | Expression | Notes |
|---|---|---|
Spending multiplier | 1 / (1 − MPC) | Always > 1 if MPC is between 0 and 1 |
Tax multiplier | −MPC / (1 − MPC) | Negative sign: tax cuts raise GDP, tax increases lower it |
Balanced-budget multiplier | 1 | Equal increase in G and T raises GDP by the amount of the increase |
MPC + MPS | = 1 | Every extra unit of income is either spent or saved |
Automatic stabilisers are the reason tax revenues fell sharply during the 2008 financial crisis without anyone voting to cut taxes: incomes dropped, so people owed less.
The debate over the size of the spending multiplier is central to arguments about stimulus packages. If the multiplier is large, deficit-financed spending pays for itself partly through higher tax revenue on the extra GDP. If it is small (due to crowding out or Ricardian equivalence), the fiscal boost is more modest.
"The tax multiplier and the spending multiplier are the same size." They are not. The spending multiplier is larger because government spending enters the economy at full value on the first round, while a tax cut is partly saved.
"Automatic stabilisers fix recessions." They cushion recessions, but they are not strong enough to fully offset large downturns. Discretionary policy is often needed on top.
"Expansionary fiscal policy always raises output permanently." In the AD-AS model, the long-run effect on output is zero (output returns to potential). Only the price level is permanently affected.
"Crowding out completely cancels out fiscal stimulus." Crowding out reduces the effectiveness of fiscal policy, but in most models it does not fully offset it, especially during deep recessions when interest rates are already low.
⚠️ You will almost certainly be asked to calculate the spending multiplier and/or the tax multiplier given an MPC value. Know both formulas cold.
⚠️ Be ready to show expansionary and contractionary policy shifts on an AD-AS diagram, labelling both the short-run and long-run equilibrium.
⚠️ Understand why the spending multiplier is larger than the tax multiplier. This is a favourite multiple-choice distractor.
⚠️ Automatic stabilisers are a common short-answer topic. Be able to name at least two examples (progressive taxes, unemployment insurance) and explain the mechanism.
True or False: The tax multiplier is larger in absolute value than the spending multiplier.
Fill in the blank: If the MPC is 0.75, the spending multiplier is ______.
True or False: Automatic stabilisers require new legislation to take effect.
Fill in the blank: Expansionary fiscal policy shifts the AD curve to the ______.
True or False: In the long run, an increase in government spending raises both the price level and real GDP above potential.
Answers: 1. False. 2. 4. 3. False. 4. Right. 5. False (output returns to potential; only the price level is permanently higher).
Q: If the MPC is 0.6, what is the government spending multiplier and the tax multiplier?
A: Spending multiplier = 1 / (1 − 0.6) = 2.5. Tax multiplier = −0.6 / (1 − 0.6) = −1.5.
Q: Explain why the spending multiplier is larger than the tax multiplier in absolute value.
A: When the government spends £1, the entire pound enters the spending stream immediately. When the government cuts taxes by £1, households receive the extra pound but save a fraction of it (MPS). Only the spent fraction enters the first round of the multiplier chain, so the cumulative effect is smaller.
Q: Using the AD-AS model, describe the short-run and long-run effects of an increase in government spending.
A: In the short run, AD shifts right. Output rises above potential, employment increases, and the price level rises. In the long run, higher prices cause wages and input costs to adjust upward, shifting SRAS to the left. Output returns to its natural level, and the price level is permanently higher than before.
Q: Name two automatic stabilisers and explain how one of them works.
A: Progressive income taxes and unemployment insurance. Progressive income taxes work because, as incomes fall during a recession, taxpayers move into lower brackets and owe less tax. This happens without any legislative change and leaves households with more disposable income, partially supporting consumption.
Q: A capital income tax increase reduces investment. Through what mechanism does this occur?
A: The tax reduces the after-tax return on capital. Investors require a higher pre-tax return to justify the same level of risk, which means fewer projects are profitable at the new after-tax rate. Investment falls, reducing capital accumulation and, over time, potential output.
The multiplier concept connects directly to the Keynesian cross model (if covered earlier in your course), where equilibrium output is determined by aggregate expenditure.
Crowding out links fiscal policy to the loanable funds market and interest rate determination, which bridges into monetary policy (covered in Part 2 of these notes).
The AD-AS framework used here reappears when analysing supply shocks, monetary policy, and long-run economic growth.
fiscal policy, monetary policy, automatic stabilisers, automatic stabilizers, progressive taxation, unemployment insurance, government spending multiplier, tax multiplier, balanced budget multiplier, marginal propensity to consume, MPC, marginal propensity to save, MPS, aggregate demand, aggregate supply, AD-AS model, expansionary policy, contractionary policy, crowding out, Ricardian equivalence, discretionary fiscal policy, labour income tax, capital income tax, ECO 201, macroeconomics, University of Florida